9.1.3 A gas detection system with audible and visual alarm is to be provided for
spaces, where dangerous gas could be present. For flammable atmospheres, the BWTS
shutdown is to be activated at a flammable concentration of not more than 60 per cent of
LFL. The alarm is also to be provided at manned ballast water control station(s) and in
the engine control room, as applicable. Audible and visual alarm signals are to be
activated both locally and at the control station(s) when the flammable concentration
reaches a pre-set value, which should not be higher than 30 per cent of the LFL of the
product concerned.
9.1.4 For flammable gases and explosive atmospheres including but not limited to
hydrogen (H2), the construction, testing and performance of the gas detection
devices is to be in accordance with IEC 60079-29-1, IEC 60079-29-2, IEC 60079-29-3
and/or IEC 60079-29-4, as applicable. Where other hazards are considered, such as
toxicity, asphyxiation, corrosive and reactivity hazards, a recognised standard
acceptable to LR is to be selected with due consideration of the specific gases to be
detected and due consideration of the performance of the detection device with regards
to the specific atmosphere where it is used.
9.1.5 Failure of a BWTS power or control system is not to render the BWTS
hazardous and is not to affect the operation of essential services.
9.1.6 Active or passive monitoring systems with alarm and safeguards are to be
provided to mitigate risks and to ensure the safety of the ship and its occupants.
9.1.7 Failure of power or control systems is not to impair or restrict the
by-pass or isolation arrangements or alternatively, it is to be demonstrated that
fail-safe arrangement of valves is available to ensure the function of by-pass and
isolation arrangements.
9.1.8 By-pass and isolation valves are to be provided with position indicators to
give remote indication of valve positions.
9.1.9 Activation of by-pass or isolation arrangements is to activate an alarm in
all stations from which the ballast water operations are controlled and be automatically
recorded in control equipment.
9.1.10 Electric and electronic components are not to be installed in a hazardous
area unless they are of certified safe type for use in the area. Cable penetrations of
decks and bulkheads are to be sealed when a pressure difference between the areas is to
be maintained.
9.1.11 Deviation from normal working pressure in ballast tanks is to activate an
alarm and is to shut down the BWTS. The pressure at which shutdown is to occur is to be
set in accordance with the tank manufacturer’s recommendations.
9.1.12 When it is required to have an automatic shutdown of the BWTS for safety
reasons, this must be achieved by a safety system that is functionally independent of
the BWTS control system as far as practicable.
9.1.13 Equipment protection
- Protection is to be installed to protect UV type BWTS in accordance with
Pt 6, Ch 2, 6 System design – Protection.
- Electrolysis reactors are to be provided with at least two independent
means of monitoring their operation. The monitoring system is to initiate audible and
visual alarms in all stations from which the ballast water operations are controlled
and automatic shutdown of the BWTS in the event that an anomaly is detected.
Requirements for shutdown arrangement are clarified in Pt 5, Ch 25, 11.1 General requirements 11.1.5.
Note If a pressure relief valve is also
provided, the vent of this valve is to be led to a safe location on the open deck, as
specified in
Pt 5, Ch 25, 1.2 Definitions. The valve is
to be positioned to optimally remove gas from the electrolysis reactor.